package com.wang.leetcode;
//二叉树的中序遍历 递归
import java.util.ArrayList;
import java.util.List;

public class Solution94 {
    public class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;

        TreeNode() {
        }

        TreeNode(int val) {
            this.val = val;
        }

        TreeNode(int val, TreeNode left, TreeNode right) {
            this.val = val;
            this.left = left;
            this.right = right;
        }
    }
    public List<Integer> inorderTraversal(TreeNode root) {
        List<Integer> res = new ArrayList<>();
        inorder(root, res);
        return  res;
     }
     public void inorder(TreeNode root , List<Integer> res) {
         if(root == null) {
             return;
         }
         inorder(root.left, res);
         res.add(root.val);
         inorder(root.right, res);
     }
}
